Up to now nuclear power plant operators and suppliers have focused, for the most part, on optimizing the Nuclear Island (NI) as well as the turbine generator set to obtain more power out of their plants and to enhance plant safety and availability. Little attention has been paid to the fact that the Balance of Plant (BOP) - also known as the Conventional Island (CI) - also offers many opportunities for increasing net electric output at relatively low cost and with short payback periods.

The CI is a highly complex network of pipes, process components, and instrumentation & control systems that serve the sole purpose of efficiently and reliably converting thermal energy to electricity. At many plants, electric output can be increased by up to 4% through a variety of carefully coordinated measures without having to increase the thermal output of the reactor.

To effectively exploit these hidden resources in the CI, a supplier is needed who knows the plant from “core to condenser” and is experienced in analyzing and assessing power plants in their entirety - for this is the only way to prevent modifications from having undesirable effects on other systems.

Turnkey Expertise is the Key

Most of today's nuclear power plants were built according to the Architect-Engineer (AE) model where one company supplied the nuclear steam supply system or the NI, several companies supplied the BOP systems and all of their various tasks were coordinated by the AE. This often resulted in individual BOP systems being improved without the plant as a whole being optimized.

Framatome ANP, with its wide-ranging expertise in turnkey plant construction, follows a holistic approach: it treats the entire BOP as a single entity - the CI - while carefully accounting for its interaction with the NI at one end and the conditions of the main heat sink at the other. Also, the company systematically analyzes all CI systems and components that impact plant output. In this way, the entire plant can be optimized in terms of power production, while at the same time ensuring high plant availability and efficiency.

First Reference Project

Framatome ANP currently is performing a CI optimization study, based on this holistic approach, for the first time for a Japanese client. The study, started in June 2002, should be completed by March 2003. Working in close cooperation with the customer, possible areas for improvement are being identified, based on the present status of the plant. Technical recommendations for increasing plant efficiency are being developed with close attention paid to their cost/benefit ratio.

Options Available for Optimizing the CI to Increase Plant Output

• Increase of average reactor coolant temperature to achieve higher average main steam pressures
• Reduction of main steam pressure losses (e.g. removal of steam strainers)
• Improvement of water separation efficiency of moisture separator reheater
• Improvement of steam generator heat transfer (e.g. chemical cleaning)
• Heat recovery in steam, condensate and feedwater cycle
• Improvement of feedwater flow measurement
• Optimization of main heat sink. (e.g. increase of cooling water mass flow)